The invention concerns a annular seal able to be positioned on each end, or neck, shaped like a truncated cone, of a rolling roll, in proximity with a corresponding supporting oil-film bearing, to guarantee that the oil arriving from the bearing is sealed and at the same time to prevent water, other cooling liquid or any impurity, from entering from outside into the zone of the oil. Once coupled with the neck of the rolling roll, the seal is able to rotate therewith and to follow the axial displacements thereof.
Annular seals are able to be assembled on the tapered ends, with a conical surface, of the rolling rolls, each one between a corresponding supporting oil-film bearing and a front surface of the rolling roll, to rotate with the latter and to follow the axial displacements thereof, if any.
The function of annular seals is to guarantee, during use, that the oil arriving from the supporting bearing is sealed and at the same time prevent water and any impurities from entering from outside into the zone of the bearing.
The state of the art includes an annular seal for rolling rolls which comprises an annular body made of flexible material, shaped so as to define a through central cavity, able to be coupled with a tapered end of the rolling roll. Two substantially parallel radial appendices extend from the annular body and define an outer annular compartment, inside which, during use, a separation tooth of a fixed supporting flange is inserted.
The radial appendices are provided with terminal lips able to contact, during use, a sliding surface of the fixed supporting flange.
This conventional seal has the disadvantage that the terminal lips, which are normally made of elastomer, are subject to considerable wear, due to the sliding friction and to the impurities such as scale or suchlike contained in the cooling water and which mainly affect the lip on the water seal side. The friction also causes a considerable over-heating of the terminal lips.
This disadvantage affects the duration of the seals, and therefore it is necessary to have them replaced frequently.
The present Applicant has devised, designed and embodied the seal according to the invention to overcome this and other shortcomings of conventional seals, and to achieve the purposes explained hereafter.
The seal according to the invention is set forth and characterized in the main claim, while the dependent claims describe other innovative features of the invention.
One purpose of the invention is to achieve a seal which is very reliable from the point of view of the static and dynamic seal, both on the oil side and on the water side, and which, at the same time, has a considerable working life, substantially without losing its initial characteristics.
Another purpose of the invention is to achieve a seal wherein the elements subject to particular wear, due to friction and impurities, are made of a material with a low friction coefficient, lower than that of the flexible material of which the annular body of the seal is made.
In accordance with these purposes, the annular seal according to the invention comprises an annular body of flexible material, shaped so as to define a central cavity able to be coupled with a tapered end of the rolling roll, between a supporting bearing and a front surface of the rolling roll, and a pair of substantially parallel radial appendices which define an outer annular compartment in which, during use, a separation element of a fixed supporting flange is able to be arranged. The terminal sealing lips of the radial appendices, at least on the side arranged towards the afore-said annular compartment, are provided with anti-wear elements able to contact, during use, a sliding surface of the fixed supporting flange.
The anti-wear elements are advantageously made of self-lubricating material, such as PTFE with added bronze, with a very high resistance to abrasion, so as to drastically reduce the heat developed through friction due to the movements of translation, but especially of rotation, of the seal with respect to the fixed supporting flange.
Advantageously, the anti-wear elements are made in a single piece with the sealing lips and are vulcanized directly onto the material of which the annular body is made, instead of being glued after the seal has been molded.
The width of the outer compartment, defined by the two radial appendices, is such as to permit, during use, the total axial displacement of the rolling roll without the inner walls of the radial appendices, during normal functioning, coming into contact with the separation element of the fixed supporting flange.
Moreover, the position of the radial appendices, with respect to the annular body from which they extend, is such that, during use, for every axial position of the rolling roll, the sealing lips are always in contact with the sliding surface of the fixed supporting flange.
With the sole purpose of creating a further barrier to the leakage of oil from one side and the entry of water on the other, the annular body has a plurality of tiny circular ridges, having a height comprised between about 1 and 2 mm and arranged inside the through central cavity.
According to another characteristic feature of the invention, the seal also comprises a plurality of radial ribs coupled with at least one of the afore-said radial appendices to prevent the latter from being deformed by the separation element of the fixed flange during the operations to assemble or remove the seal itself.
A rigid disk, advantageously metal, is able to be coupled, during use, with the annular body of the seal. To be more exact, the disk comprises a front wall able to be arranged parallel to the front surface of the rolling roll, an inner tapered part, able to laterally contact the annular body of the seal, and an outer part, also tapered, able to facilitate, during use, the expulsion of the water due to the centrifugal force.